HP StorageWorks P9000 - Disk Arrays User Manual page 9

Figure 3 Update copy operation
Although an initial copy completes and pair status changes to Duplex, the data in the S-VOL and
T-VOL may not be the same because the copy of the update data is performed asynchronously.
To ensure that S-VOL and T-VOL data are the same at a certain point in time, the pair must be split.
CAUTION: If the copy operation is completed without any host I/O, the data in the S-VOL and
the data in the T-VOL may not be the same. To make the S-VOL data and the T-VOL data equal,
split the pair and make the pair status Split.
Initial and update copy operations 9